The present invention relates to an improved process for the preparation of a plasminogen tissual activator as described in French Pat. No. 73 42981 filed on Dec. 3, 1973 in the name of Pierre Fabre S.A. and in the equivalent patents, U.S. Pat. No. 3,998,937 and British Pat. No. 1,492,959 which are mentioned here as references.
Hereinafter, the terms "plasminogen tissual activator" or "plasminogen activator" essentially designate an activator described in the above-mentioned patents.
The process for the preparation of the said plasminogen tissual activator described in the above-mentioned patents has the disadvantage of necessitating numerous stages of absorption in saline solutions of differing concentration before obtaining a high purity product.
We have devised a new process for the preparation on a large scale of this plasminogen activator making use of the natural affinity of tissual plasminogen activators for fibrin. In effect, fibrin has the property of selectively fixing this plasminogen activator from among other inactive proteins and of thus effecting very rapid separation.
This process has the advantage that it can be carried out on a large scale and thus of producing a plasminogen activator having a specific activity which is substantially better than that of the product forming the subject of the main application.
The direct use of fibrin, such as described by certain authors, presents numerous problems, of which the main ones are that it is not possible to work on a large scale and on the other hand to liberate at the same time only the plasminogen activator, the soluble fragments of fibrin possessing undesirable properties.
The process forming the object of the present invention has the advantage of isolating from fibrin the soluble fragments carrying the fixing site for the plasminogen activator and of fixing these fragments by covalence on an insoluble matrix. The support thus prepared is totally insoluble. It possesses mechanical properties suitable for industrial application and can be reused numerous times without loss of its properties.
Moreover, the said activator can be combined with a sulphated polysaccharide, as described in Certificate of Addition No. 75 13 932 filed on May 5, 1975, and can benefit from the potentiation resulting from this combination.